Should I delete the carts?
One thing I have to say about OSHPark is that they seem to struggle with solder mask layers. I just received 2 batches of boards (unrelated projects) with incorrect solder masks. I checked the projects on OSHPark and the automated renders look fine. However on my boards they are not! One one board there is mask where there shouldn't be (so now I have to hand scrape it off so I can solder to the copper underneath). On the other board there is no mask where there should be, so I have no guide at all when soldering the components down.
Thankfully I can more or less use both boards as they are not critical. It's just frustrating, especially seen as I've been waiting 3 weeks for the boards.
Oshpark will remake errors. Doesn’t sound like you’d wish to wait another 3 weeks though.
Back side of the 7135 layers were a bit squiffy too, but functional
This is a phenomenal resource.
I’m surprised at the sole emphasis on linear divers though. Are there no open source step-down/buck circuits?
If you know of any working schematics…maybe someone can design the PCB
Plus I think the FET and 7135 ATtiny13 driven has TONS of research already done and is MUCH simpler than buck circuits of any sort of high power output
Alot easier to design and proven to work…
I can only speak for myself but it's basically because they are bloody difficult to get right and take a lot of time to get working. For the most part, linear and DD drivers take all of 5 minutes to get a basic design working. I'm more than happy to open source the basic stuff but the drivers that take hundreds of hours to get right are a different story.
On the other hand I'd be more than happy to contribute to a team designed open source switch mode driver.
It’s not so much an emphasis as hopefully a starting point. A bunch of boards were designed in a short time and it made sense to me to get them all together. Any flashlight related Oshpark projects would fit the bill and I’d love to have boost and buck boards posted as well. Help us find them!
Are there any drivers in the community based on the AX2003 ?
Datasheets? Schematics?
Yep, available online. I can’t seem to copy /paste a clean link from my phone, but if you Google it, the first result is a datasheet. It’s about the simplest buck IC you could ask for.
Anyone up for making a parallel 4 x AA carrier?
The easiest of easy.
I'm working on a series triple AA carrier for djozz at the moment. If I get that done tonight I'll do a parallel carrier as well. Any specifics? BATT+ and BATT- available at the front? Or BATT+ front, BATT- rear? Overall diameter requirement or just as small as possible with 4xAA cells?
“re-inventing the wheel”?
or were you being serious? 
This is one of my AX2003 board in EAGLE. Dropbox - 22MM_2.5A_104R.zip - Simplify your life You may download and have a trial.
Please note that the bottom layer is the ground which work as a thermal pad.
If you want batt+ front, batt- rear, it seems like a waste to pay oshppark for that. Pretty much just a couple sheet metal or copper plates with springs.
What will be used as the supports / pillars. I’ve been thinking about what could be used that should be commonly available anywhere.
Seems like a good way to short out 4 cells.
You do have to be intelligent about decisions re: surface area. This may be a year old now, but it’s still roughly accurate:
http://www.meatandnetworking.com/resources/cheap-prototype-pcb-comparison/
An easier rule of thumb (at least the one I follow) is that as soon as your 3x boards from Oshpark hit just above the $10 mark, you’re better moving over to iTead, where that $10 (a bit more because they charge shipping) will get you 10x copies instead.
With parallel? Isolation is easy, no?
Maybe I’m cheap? PCBs certainly looks better & more finished. $9 for 4xAA top plates +$9 for bottoms. Pushed mine down to $7.45 if its squared off a bit.
Sorry if that came across as abrupt but your description of two metal plates was a bit lacking in detail. Sure I could make something and often do but other times it’s nice to have it already done. There are several more options I’d like to see as well and I like your use of solid wire to beef up the vias.